Following the occupation of Iran in 1941, WD locomotives were required to operate the Persian Corridor supply route, delivering war materials to the Soviet Union via the Trans-Iranian Railway. 163 8F were dispatched to Iran in 1941-42, but only 143 arrived (12 being lost at sea (246-444, 445, 608, 617, 619, 622 (latter 4 former LMS 8066, 8068, 8071, 8087)) and 8 returned to Britain with sea damage). These operated as Iranian State Railways’ Class 41.

The arrival of US Army Transportation Corps units in Iran with their own locomotives (including diesels which were more suitable for use in desert regions) made many of the 8Fs redundant, and 50 locomotives were transferred to the Middle East Forces in 1944. At the end of the war the need for steam locomotives in Iran was further reduced and another 71 locomotives left for the MEF and Iraq in 1945-48. The remaining 22 locomotives in Iran had all been withdrawn by 1963.